Measurement of the Branching Fraction of the Decay $\boldsymbol{B^{+}\toπ^{+}π^{-}\ell^{+}ν_\ell}$ in Fully Reconstructed Events at Belle
The Belle Collaboration, C. Beleño, A. Frey, I. Adachi, H. Aihara, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, P. Behera, J. Bennett, F. Bernlochner, V. Bhardw… 展开作者
The Belle Collaboration, C. Beleño, A. Frey, I. Adachi, H. Aihara, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, P. Behera, J. Bennett, F. Bernlochner, V. Bhardwaj, T. Bilka, J. Biswal, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, D. Červenkov, P. Chang, A. Chen, K. Chilikin, K. Cho, Y. Choi, D. Cinabro, S. Cunliffe, N. Dash, F. Di Capua, J. Dingfelder, Z. Doležal, T. V. Dong, S. Eidelman, D. Epifanov, J. E. Fast, T. Ferber, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, Y. Guan, O. Hartbrich, K. Hayasaka, H. Hayashii, W. -S. Hou, K. Inami, A. Ishikawa, M. Iwasaki, W. W. Jacobs, H. B. Jeon, Y. Jin, K. K. Joo, C. Kiesling, B. H. Kim, D. Y. Kim, K. -H. Kim, S. H. Kim, Y. -K. Kim, T. D. Kimmel, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križan, R. Kroeger, P. Krokovny, T. Kuhr, R. Kulasiri, R. Kumar, A. Kuzmin, Y. -J. Kwon, K. Lalwani, S. C. Lee, L. K. Li, Y. B. Li, L. Li Gioi, J. Libby, K. Lieret, D. Liventsev, T. Luo, J. MacNaughton, C. MacQueen, M. Masuda, T. Matsuda, M. Merola, K. Miyabayashi, G. B. Mohanty, T. J. Moon, T. Mori, M. Mrvar, M. Nakao, N. K. Nisar, S. Nishida, S. Ogawa, H. Ono, P. Oskin, P. Pakhlov, G. Pakhlova, S. Pardi, H. Park, S. Patra, T. K. Pedlar, R. Pestotnik, L. E. Piilonen, T. Podobnik, E. Prencipe, M. T. Prim, A. Rostomyan, N. Rout, G. Russo, D. Sahoo, Y. Sakai, S. Sandilya, A. Sangal, T. Sanuki, V. Savinov, G. Schnell, C. Schwanda, A. J. Schwartz, B. Schwenker, Y. Seino, K. Senyo, M. E. Sevior, M. Shapkin, J. -G. Shiu, B. Shwartz, A. Sokolov, E. Solovieva, M. Starič, Z. S. Stottler, J. F. Strube, T. Sumiyoshi, W. Sutcliffe, M. Takizawa, K. Tanida, F. Tenchini, M. Uchida, T. Uglov, S. Uno, P. Urquijo, S. E. Vahsen, R. Van Tonder, G. Varner, K. E. Varvell, C. H. Wang, E. Wang, M. -Z. Wang, P. Wang, X. L. Wang, M. Watanabe, E. Won, X. Xu, W. Yan, S. B. Yang, H. Ye, Y. Yusa, Z. P. Zhang, V. Zhilich, V. Zhukova
We present an analysis of the exclusive $B^{+}\toπ^{+}π^{-}\ell^{+}ν_{\ell}$ decay, where $\ell$ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The analysis uses the full $Υ(4S)$ data sample collected by the Belle detector, corresponding to 711 fb$^{-1}$ of integrated luminosity. We select the events by fully reconstructing one $B$ meson in hadronic decay modes, subsequently determining the properties of the other $B$ meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of ${{\cal B}(B^{+}\to π^{+}π^{-}\ell^{+}ν_{\ell})= [22.7 ^{+1.9}_{-1.6} (\mathrm{stat}) \pm 3.5(\mathrm{syst}) ]\times 10^{-5}}$, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.
Measurements of $\boldsymbol{B\rightarrow Kπ}$ and $\boldsymbol{B\rightarrow ππ}$ Branching Fractions and $\boldsymbol{\mathcal{A}_{CP}}$ Asymmetries at Belle II
Belle II 测量了多种 $B\to K\pi$ 和 $B\to\pi\pi$ 衰变的分支比及直接 CP 不对称性，通过同位旋求和规则检验标准模型，并测量了 CKM 角 $\phi_2$ 相关的衰变，结果与标准模型预期一致。
Search for B -> tau nu and B -> K nu nubar Decays with a Fully Reconstructed B at Belle
我们在KEKB非对称能量B工厂的Belle探测器上，利用Upperion（4S）共振采集了253 fb^-1的数据样本，对衰变B -> tau nu和B -> K nu nubar进行了搜索。通过选择具有一个完全重建的B的事件样本来抑制组合和连续背景。对事件另一侧B的衰变产物进行分析，以寻找B -> tau nu和B -> K nu nubar衰变。我们没有发现信号的显著证据，并将90%置信水平的上限设为B（B -> tau nu）< 1.8*10^-4和B（B -> K nu nubar）< 3.6*10^-5。
Measurements of Charmed Meson Lifetimes and Search for $D^0$-$\overline{D}^0$ Mixing with the Belle Experiment
用11.1 fb $^{-1} of data collected with the Belle detector at KEKB. Each candidate is fully reconstructed to identify the flavor of the charmed meson. The lifetimes are measured to be $ τ（D^0）=（414.5 \pm 1.7）$ fs, $ τ（D^+）=（1029 \pm 12）$ fs and $ τ（D^+）=（488.4^{+7.8}-7.7}）$ fs, where the error is statistical only. The mixing parameter $ y_{CP} $ is also measured to be $ y_{CP} =（1.16^{+1.67}-1.65}（stat.））%测量了粲介子的寿命$ through the lifetime difference of $ D^0$介子衰变到CP混合态和CP本征态。
New Measurements of Time-Dependent CP-Violating Asymmetries in b --> s Transitions at Belle
我们基于在KEKB能量非对称e+e-对撞机的Belle探测器上的Upperion（4S）共振处收集的275 x 10^6个BBbar对的样本，对B 0--> phi K 0，K+ K-Ks，f0（980）Ks，eta' Ks，omega Ks，Ks pi 0和K*0 gamma（K*0 --> Ks pi 0）衰变中CP破坏参数进行了新的测量。一个中性B介子在一个特定的衰变通道中被完全重建，伴随的B介子的味道从它的衰变产物中被识别。从两个B衰变之间的适当的时间间隔的分布中的不对称性获得每个衰变模式的CP-违反参数。所有结果都是初步的。
本文研究了稀有衰变B -> h（*）nu nubar，其中h（*）代表轻介子.使用KEKB e+e对撞机Belle探测器收集的5.35亿个BBbar对的数据样本。信号候选者需要有一个伴随的B介子完全重建在强子模式和信号侧粒子符合一个单一的h（*）介子。未观察到显著信号，我们将分支分数的上限设定为90%置信水平。对B 0-> K*0 nu nubar和B+ -> K+ nu nubar衰变的限制比以前的限制更严格，而对B 0-> K 0 nu nubar，pi 0 nu nubar，rho 0 nu nubar，phi nu nubar和B+ -> K*+ nu nubar，rho+ nu nubar的首次搜索也被报道。
A Hierarchical NeuroBayes-based Algorithm for Full Reconstruction of B Mesons at B Factories
我们描述了一种新的B介子完全重建算法，该算法是为B工厂KEKB的Belle实验设计的，KEKB是一台非对称e+e对撞机，在运行期间收集了771.6 x 10^6个BBbar对的数据样本。为了最大限度地提高重建的B衰变通道的数量，它利用了一个分层的重建过程和概率演算，而不是经典的选择切割。多变量分析软件包NeuroBayes被广泛用于在尽可能高的效率、鲁棒性和可接受的CPU时间消耗之间保持平衡。总共使用71个神经网络重建了1104个排他性衰变通道。总体而言，我们分别在0.28%或0.18%的BBbar事件中正确重建了一个B+/-或B 0候选。与Belle实验中使用的基于切割的经典重建算法相比，根据所考虑的分析，这是效率的大约2倍的改进。新框架还具有自由选择完全重构样品的所需纯度或效率的能力。如果期望与经典全重构代码相同的纯度~ 25%，则效率仍然高出近2倍。另一方面，如果选择与经典完全重构相似的效率水平，则纯度从约25%上升到近90%。
